Myotonic dystrophy type 1 (DM1) is a neuromuscular disorder presenting with major muscle impairments. However, few studies have addressed muscle strength progression using quantitative methods. The aims of this study were to document muscle strength changes in eight muscle groups among adults with DM1 over a 9-year period, and to compare this progression between phenotypes (adult and late-onset) and sex. Patients with a genetic diagnosis of DM1 with the late-onset or the adult phenotype were recruited at baseline through the clinical registry of the Saguenay Neuromuscular Clinic...

External supports that reduce ankle joint mobility such as ski-boots can impair postural control of healthy participants. Although this disruptive effect has been attributed to the rigidity of the external supports, the results remained controversial and no study has been conducted in order to evaluate the influence of ski-boots rigidity. Hence, the question about the influence of ankle support rigidity on postural control remains open. This study was therefore undertaken in order to investigate the effect of ski-boots rigidity on postural control...

The aim of the present study was to evaluate the radiologic factors related to ankle pain before and after total knee arthroplasty (TKA) among patients with a varus osteoarthritic knee. Fifty-five patients (65 ankles) with a varus osteoarthritic knee who had undergone TKA and were followed up for >24 months were enrolled. For clinical assessment, the visual analog scale for pain and the American Orthopaedic Foot and Ankle Society ankle-hindfoot scale were used. For radiologic assessment, the mechanical axis deviation angle, talar tilt, tibial anterior surface angle, distal medial clear space, medial tibiotalar joint space, frontal tibial ground angle, and hindfoot alignment view angle were measured...

BACKGROUND: Compensatory pelvis, hip- and knee movements are reported after stroke to overcome insufficient foot-clearance. Ankle-foot orthoses (AFOs) are often used to improve foot-clearance, but the optimal timing of AFO-provision post-stroke is unknown. Early AFO-provision to prevent foot-drop might decrease the development of compensatory movements, but it is unknown whether timing of AFO-provision affects post-stroke kinematics. RESEARCH QUESTIONS: 1) To compare the effect of AFO-provision at two different points in time (early versus delayed) on frontal pelvis and hip, and sagittal hip and knee kinematics in patients with sub-acute stroke...

The ability to walk around in a natural environment requires the capacity to cope with unexpected obstacles that may disrupt locomotion. One such mechanism is called the stumbling corrective reaction (SCR) that enables animals to step over obstacles that would otherwise disturb the progression of swing movement. Here we use in vivo motion analysis and physiological recording techniques to describe the SCR in mice. We show that SCR can be elicited consistently in mice during locomotion by inserting an obstacle along the path of leg movement during swing phase...

Despite the prevalence of pre-obesity and obesity, the physical capabilities of pre-obese/obese individuals are not well documented. As an effort to address this, this study investigated the pre-obesity and obesity impacts on joint range of motion (RoM) for twenty-two body joint motions. A publicly available passive RoM dataset was analysed. Three BMI groups (normal-weight, pre-obese, and obese [Class I]) were statistically compared in joint RoM. The pre-obese and obese groups were found to have significantly smaller RoM means than the normal-weight for elbow flexion and supination, hip extension and flexion, knee flexion, and ankle plantarflexion...

BACKGROUND: Hamstring injuries remain a significant injury burden in sports such as soccer that involve high-speed running. It has repeatedly been identified as the most common noncontact injury in elite male soccer, representing 12% of all injuries. As the incidence of hamstring injuries remains high, investigations are aimed at better understanding how to prevent hamstring injuries. Stretching to improve flexibility is commonly used in elite-level sports, but risk factor studies have reported contradicting results, leading to unclear conclusions regarding flexibility as a risk factor for hamstring injuries...

BACKGROUND: Restoration of correct coronal alignment is one of the main goals of total knee arthroplasty (TKA). Traditionally, TKA has been considered successful when a neutral mechanical hip-knee-ankle (HKA) axis within 3° is achieved. Recent studies have reported no differences or improved clinical outcomes following a slight under-correction of the HKA axis for a varus knee. However, the influence of under-correction of a valgus knee has not been reported. This study investigated the influence of post-operative HKA alignment in TKA patients with valgus deformity on clinical outcomes...

PURPOSE: This study aims to develop an accurate and robust phase-unwrapping method that works effectively under severe noise, rapid-varying phase, and disconnected regions for water-fat Dixon MRI. METHODS: The proposed method first segments the phase map into blocks by automatically detecting phase jumps, and then clusters the pixels near phase jumps into residual pixels. Thereafter, the proposed method sequentially performs intrablock, interblock, and residual-pixel unwrapping using the local surface fitting approach...

After incomplete spinal cord injury (SCI), neural circuits may be plastically reconstructed to some degree, resulting in extensive functional locomotor recovery. The present study aimed to observe the post-SCI locomotor recovery of rhesus monkey hindlimbs and compare the recovery degrees of different hindlimb parts, thus revealing the recovery process of locomotor function. Four rhesus monkeys were chosen for thoracic hemisection injury. The hindlimb locomotor performance of these animals was recorded before surgery, as well as 6 and 12 weeks post-lesion...

Cerebral palsy is known to generally limit range of motion and force producing capability during movement. It also limits sprint performance, but the exact mechanisms underpinning this are not well known. One elite male T36 multiple-Paralympic sprint medallist (T36) and 16 well-trained able-bodied (AB) sprinters each performed 5-6 maximal sprints from starting blocks. Whole-body kinematics (250 Hz) in the block phase and first two steps, and synchronised external forces (1,000 Hz) in the first stance phase after block exit were combined to quantify lower limb joint kinetics...

Stiffness describes the resistance of a body to deformation. In regard to athletic performance, a stiffer leg-spring would be expected to augment performance by increasing utilisation of elastic energy. Two-dimensional spring-mass and torsional spring models can be applied to model whole-body (vertical and/or leg stiffness) and joint stiffness. Various tasks have been used to characterise stiffness, including hopping, gait, jumping, sledge ergometry and change of direction tasks. Appropriate levels of reliability have been reported in most tasks, although they vary between investigations...

Proprioceptive afferent activities recorded by a multichannel microelectrode have been used to decode limb movements to provide sensory feedback signals for closed-loop control in a functional electrical stimulation (FES) system. However, analyzing the high dimensionality of neural activity is one of the major challenges in real-time applications. This paper proposes a linear feature projection method for the real-time decoding of ankle and knee joint angles. Single-unit activity was extracted as a feature vector from proprioceptive afferent signals that were recorded from the L7 dorsal root ganglion during passive movements of ankle and knee joints...

Objective: To investigate the relationship between functional level and muscle thickness (MT) of the rectus femoris (RF) and the gastrocnemius (GCM) in young children with cerebral palsy (CP). Methods: The study participants were comprised of 26 children (50 legs) with spastic CP, aged 3-6 years, and 25 age-matched children with typical development (TD, 50 legs). The MT of the RF, medial GCM, and lateral GCM was measured with ultrasound imaging. The functional level was evaluated using the Gross Motor Function Measurement-88 (GMFM-88), Gross Motor Function Classification System (GMFCS), and based on the mobility area of the Korean version of the Modified Barthel Index (K-MBI)...

[Purpose] An estimation model of the knee and ankle joint angles during the extension phase was proposed in the previous study. However, it had limited use because of the fixed initial lower limb angle before standing up. This study aimed to propose a new estimation model of the initial lower limb angle to improve the angle estimation during extension phase. [Subjects and Methods] Seven healthy male volunteers were enrolled. The new estimation model approximated the initial lower limb angle using a force sensor plate that measured the plantar pressure of the subjects...

Plantarflexion resistance of an ankle-foot orthosis (AFO) plays an important role to prevent foot-drop, but its impact on push-off has not been well investigated in individuals post-stroke. The aim of this study was to investigate the effect of plantarflexion resistance of an articulated AFO on ankle and knee joint power of the limb wearing the AFO in individuals post-stroke. Gait analysis was performed on 10 individuals with chronic stroke using a Vicon 3-dimensional motion capture system and a Bertec split-belt instrumented treadmill...

BACKGROUND: Hip rotation kinematics during gait is a key parameter to support clinical decision making, for example in children with lower limb torsional deformities. However, hip rotation kinematics is also one of the least repeatable parameter because it is difficult to locate the position of the medio-lateral axis of the femur. Functional knee calibration provides an alternative to locate the medio-lateral axis of the femur and may be performed retrospectively, using the movement of the knee joint during gait...

BACKGROUND: Achieving proper rotational alignment of the femoral component in total knee arthroplasty (TKA) for valgus knee is challenging because of lateral condylar hypoplasia and lateral cartilage erosion. Gap-based navigation-assisted TKA enables surgeons to determine the angle of femoral component rotation (FCR) based on the posterior condylar axis. This study evaluated the possible factors that affect the rotational alignment of the femoral component based on the posterior condylar axis...